Construction machinery is used in renovating, reconstructing and extending buildings, for example. Wall saws are used for cutting and extending openings for doors, windows and light wells, etc., corrective work on facades, partition walls and garden walls, etc., and controlled demolition of concrete. Wall saws and similar construction machinery have a prime mover, such as a motor, and a rotary tool driven by the motor.
A wall saw usually includes a rack, i.e. a toothed bar or rod, intended to be attached to and equidistantly spaced from the wall, which is to be sawed through. A carriage carries a drive motor for the circular saw blade and is movable along the rack by means of another motor. The saw blade is mounted at the free end of a pivotal arm attached to the carriage and housing a transmission for transferring the rotation of the drive motor shaft to the saw blade. The pivotal arm, or transmission housing, is swung toward and away from the wall by a third motor.
In a wall saw, the tool is a circular saw blade equipped with cutting diamond segments. Generally, heavy duty wall saws are driven hydraulically, see U.S. Pat. No. 6,955,167 B2, US 2006/0201492 A1, US 2007/0163412 A1, and U.S. Pat. No. 5,887,579, for example. However, hydraulic wall saws are comparatively heavy and not easy to set up, and comparatively low-weight electric wall saws, such as the one disclosed in US 2006/0189258 A1, for example, have been introduced on the market.
In US 2006/0189258 A1 the saw process is at least partly automated by using a control program that is realized with programmable control means, displacement sensor, and pivot angle sensor.